Beam steering optics for virtual reality systems

ABSTRACT

A near-eye display system includes a display panel to present image frames to the eyes of a user for viewing. The system also includes a beam steering assembly facing the display panel that is configurable to displace a light beam incident on the beam steering assembly, thereby laterally shifting light relative to an optical path of the light beam incident on the beam steering assembly. A method of operation of the near-eye display system includes configuring the beam steering assembly in a first configuration state so that the beam steering assembly displaces a light beam incident on the beam steering assembly, such that the displaced light beam is laterally shifted relative to an optical path of the light beam.

BACKGROUND

Head-mounted displays (HMDs) and other near-eye display systems canutilize an integral lightfield display or other computational display toprovide effective display of three-dimensional (3D) graphics. Generally,the integral lightfield display employs one or more display panels andan array of lenslets, pinholes, or other optic features that overlie theone or more display panels. The HMDs and other near-eye display devicesmay have challenges associated with the limited pixel density of currentdisplays. Of particular issue in organic light emitting diode(OLED)-based displays and other similar displays is the relatively lowpixel fill factor; that is, the relatively large degree of “black space”between pixels of the OLED-based displays. While this black space isnormally undetectable for displays having viewing distances greater thanarm's length from the user, in HMDs and other near-eye displays thisblack space may be readily detectable by the user due to the closeproximity of the display to the user's eyes. The visibility of thespacing between pixels (or sub-pixels) is often exacerbated due tomagnification by the optics overlying the display panel. Therefore,there occurs a screen-door effect, in which a lattice resembling a meshscreen is visible in an image realized in the display, which typicallyinterferes with user immersion in the virtual reality (VR) or augmentedreality (AR) experience.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerousfeatures and advantages made apparent to those skilled in the art byreferencing the accompanying drawings. The use of the same referencesymbols in different drawings indicates similar or identical items.

FIG. 1 is a diagram illustrating an arrangement of components of anear-eye display system utilizing a beam steering assembly to projectimagery in accordance with some embodiments.

FIG. 2 is a diagram illustrating a cross-section view of animplementation of the near-eye display system of FIG. 1 for providingsuper-resolution imagery in accordance with some embodiments.

FIG. 3 is a diagram illustrating a diffractive beam steering element foruse in the near-eye display system of FIG. 1 in accordance with someembodiments.

FIG. 4 is a diagram illustrating a refractive beam steering element foruse in the near-eye display system of FIG. 1 in accordance with someembodiments.

FIG. 5 a diagram illustrating another refractive beam steering elementfor use in the near-eye display system of FIG. 1 in accordance with someembodiments.

FIG. 6 is a flow diagram illustrating a method for sequential display ofimages to provide a super-resolution image display in the near-eyedisplay system of FIG. 1 in accordance with some embodiments.

FIG. 7 is a diagram illustrating a method of generating passivesuper-resolution images in accordance with some embodiments.

DETAILED DESCRIPTION

FIGS. 1-7 illustrate various systems and techniques for providingoptical beam steering in a near-eye display system or imaging system. Asdescribed in further detail below, a head mounted display (HMD) or othernear-eye display system implements a beam steering assembly disposedbetween a display panel and a user's eye. The beam steering assembly canbe utilized to enhance the resolution of the display panel or tocompensate for the “screen-door” effect using a time-multiplexedapproach to displaying a sequence of two or more images that areperceived as a higher-resolution image by the user through exploitationof the visual persistence effects of the human eye. In someimplementations, the near-eye display system projects time-multiplexedimages at a higher display rate such that two or more of the imageshaving different visual information are effectively combined by thehuman visual perception system into a single “super-resolution” image;that is, an image with an effective resolution higher than the nativeresolution of the display panel. In other implementations, the near-eyedisplay system projects two or more adjacent images having the samevisual information but are spatially shifted via the beam steeringapparatus relative to each other so as to be perceived by the user as animage with light emitting elements of increased apparent size, and thuseffectively covering the non-emissive portions between the lightemitting elements of the display.

FIG. 1 illustrates a near-eye display system 100 for implementation in ahead mounted device (HMD), heads-up display, or similar device inaccordance with some embodiments. As depicted, the near-eye displaysystem 100 includes a computational display sub-system 102. The near-eyedisplay system 100 further can include other components, such as aneye-tracking subsystem, an inertial measurement unit (IMU), audiocomponentry, and the like, that have been omitted for purposes ofclarity. The computational display sub-system 102 includes a left-eyedisplay 104 and a right-eye display 106 mounted in an apparatus 108(e.g., goggles, glasses, etc.) that places the displays 104, 106 infront of the left and right eyes, respectively, of the user.

As shown by view 110, each of the displays 104, 106 includes at leastone display panel 112 to display a sequence or succession of near-eyeimages, each of which comprises an array 114 of elemental images 116.The display panel 112 is used to display imagery to at least one eye 118of the user in the form of a normal image (e.g., for super-resolutionimplementations) or a lightfield (e.g., for lightfield implementations).In some embodiments, a separate display panel 112 is implemented foreach of the displays 104, 106, whereas in other embodiments the left-eyedisplay 104 and the right-eye display 106 share a single display panel112, with the left half of the display panel 112 used for the left-eyedisplay 104 and the right half of the display panel 112 used for theright-eye display 106.

As depicted, the near-eye display system 100 includes a beam steeringassembly 120 overlying the display panel 112 so as to be disposedbetween the display panel 112 and the at least one eye 118 of a user.Cross view 122 depicts a cross-section view along line A-A of the beamsteering assembly 120 overlying the display panel 112. The beam steeringassembly 120 includes a stack of one or more optical beam steeringelements, such as the two optical beam steering elements 124, 126illustrated in FIG. 1, each optical beam steering element configured toreplicate and displace incident light rays originating from the displaypanel 112.

The near-eye display system 100 also includes a display controller 130to control the display panel 112 and, in some embodiments, a beamsteering controller 132 to control the operation of the beam steeringassembly 120. As also shown in FIG. 1, the near-eye display system 100also includes a rendering component 134 including a set of one or moreprocessors, such as the illustrated central processing unit (CPU) 136and graphics processing units (GPUs) 138, 140 and one or more storagecomponents, such as system memory 142, to store software programs orother executable instructions that are accessed and executed by theprocessors 136, 138, 140 so as to manipulate the one or more of theprocessors 136, 138, 140 to perform various tasks as described herein.Such software programs include, for example, rendering program 144comprising executable instructions for an optical beam steering andimage rendering process, as described below.

In operation, the rendering component 134 receives rendering information146 from a local or remote content source 148, where the renderinginformation 146 represents graphics data, video data, or other datarepresentative of an object or scene that is the subject of imagery tobe rendered and displayed at the display sub-system 102. Executing therendering program 144, the CPU 136 uses the rendering information 146 tosend drawing instructions to the GPUs 138, 140, which in turn utilizethe drawing instructions to render, in parallel, a series of imageframes 150 for display at the left-eye display 104 and a series oflightfield frames 152 for display at the right-eye display 106 using anyof a variety of well-known VR/AR computational/lightfield renderingprocesses.

As described in greater detail herein, the beam steering assembly 120laterally displaces, or “shifts” the position of pixels in the imageframes 150, 152 to fill in non-emissive portions of the display panel112. For example, in some embodiments, the beam steering assembly 120shifts the position of successive images displayed at the display panel112 so as to project to the user a super-resolution image or ahigher-resolution lightfield due to the succession of images effectivelybeing superimposed due to the visual persistence effect of the humanvisual system. In other embodiments, the beam steering assembly 120replicates pixels of each given image and laterally displaces thereplicated pixels so as to project an image with pixels of a perceivedlarger size (e.g., due to increased effective pixel count) that concealsthe non-emissive space between pixels. It will be appreciated thatalthough described in the context of the near-eye display system 100,the beam steering described herein may be used for any type of VR or ARsystem (e.g., conventional magnifier displays, computational displays,see-through displays, and the like).

FIG. 2 illustrates a cross-section view of an implementation 200 of thenear-eye display system 100 for providing super-resolution imagery tothe eye 118 of the user in accordance with at least one embodiment ofthe present disclosure. In this example, the display panel 112 comprisesan array of pixels, which typically are arranged as an interwovenpattern of sub-pixels of different colors, such as red, green, and blue(RGB) sub-pixels, and wherein the spatial persistence effects of humanvision result in adjacent sub-pixels of different colors to be perceivedas a single pixel having a color represented by a blend of the adjacentsub-pixels and their respective intensities. For ease of illustration,the display panel 112 is not depicted to scale, and is depicted ashaving only five sub-pixels in the cross-section (sub-pixels 202, 204,206, 208, 210), whereas a typical display would have hundreds orthousands of sub-pixels along the cross-section, and thus it will beappreciated that the dimensions of the sub-pixels 202-210, and thenon-emissive space in between the sub-pixels (e.g., non-emissive space212 between sub-pixels 206 and 208) is significantly exaggeratedrelative to the other components of the implementation 200.

Further, to aid in illustration of the operation of the beam steeringassembly 120, the implementation 200 of FIG. 2 illustrates the beamsteering assembly 120 as having only a single optical beam steeringelement 214. Moreover, in FIG. 2, the user's eye 118 is depicted as alens 216 representing the lens of the eye 118 and a panel 218representing the retinal plane of the eye 118. As such, the panel 218 isalso referred to herein as “retina 218.” Further, the implementation 200includes a magnifier lens assembly 220 (not shown in FIG. 1 for ease ofillustration) overlaying the display panel 112 such as to be disposedbetween the optical beam steering element 214 and the eye 118 of theuser. Although illustrated in FIG. 2 to be a single lens, in otherembodiments, the magnifier lens assembly 220 includes a lenslet array(not shown) with each lenslet focusing a corresponding region of thedisplay panel 112 onto the lens 216 of the eye. It also should be notedthat while FIG. 2 depicts an optical configuration with a single lensand the optical beam steering element 214 between the display panel 112and the eye 118, in a typical implementation the optical system maycomprise a larger number of lenses, prisms, or other optical elementsbetween the display panel 112 and the eye 118.

As shown, the optical beam steering element 214 is configured toreplicate light originating from sub-pixel 206 and displace thereplicated sub-pixel such that the eye 118 perceives the replicatedsub-pixel as originating from the non-emissive space 212 betweensub-pixels 206 and 208, and thus create a perception of a display havingan effective resolution of approximately twice the actual resolution ofthe display panel 112. To illustrate, in one embodiment, the beamsteering controller 132 of FIG. 1 at time to deactivates the beamsteering element 214 and the display controller 130 scans in a firstimage for display by the display panel 112. The resulting light outputby sub-pixel 206 for the first image is directed to adisplay-panel-facing surface of the beam steering element 214. Becausethe beam steering element 214 is deactivated at time t₀, the incidentlight is passed through the beam steering element 214 without lateraldisplacement to the user's eye 118, whereupon the lens 216 of the eye118 focuses the light on the retina 218 at position 222 (with light fromthe other sub-pixels 202-204 and 208-210 taking corresponding paths).

Subsequently, at time t₁, the beam steering controller 132 of FIG. 1activates the beam steering element 214, which configures the beamsteering element 214 to laterally displace incident light (e.g.,two-dimensional shift of incident light in the X- and/or Y-axisdirections of FIG. 2). The display controller 130 scans in a secondimage for display by the display panel, and the resulting light outputby sub-pixel 206 for the second image is directed to thedisplay-panel-facing surface of the beam steering element 214. Becausethe beam steering element 214 is activated at time t₁, the incidentlight is laterally displaced after passing through the beam steeringelement 214. The laterally-displaced light is passed to the user's eye118, whereupon the lens 216 of the eye 118 focuses the light on theretina 218 at position 224. The eye 118 perceives light at position 224as originating from the non-emissive space 212 between sub-pixels 206and 208 (although the light actually originated from sub-pixel 206). Thelateral displacement of incident light at the beam steering element 214results in presenting sub-pixels of the second image at positions wherenon-emissive spaces would have been perceived as black space by the eye118 from the display of the first image at time t₀. Thus, if the firstimage at time to and the second image at time t₁ are displayed in quicksuccession (i.e., within the visual persistence interval of the humaneye, which is approximately 10 ms), the human visual system perceivesthe first and second images to be overlapping. That is, in this example,the lateral displacement introduced to the light of the second image hasthe result of presenting the sub-pixels of the second image where blackspaces would have appeared to the eye 118 from the display of the firstimage, and thus the sub-pixels of the second image appear to the eye 118to occupy black spaces associated with non-emissive portions of thedisplay panel 112 for the first image.

The second image at time t₁, in some embodiments, has the same visualcontent as the first image at time t₀. In such embodiments, the eye 118perceives the two images as overlapping in a single image of the sameresolution of the first and second images (i.e., at native resolution ofthe display panel 112) but with larger perceived pixels that fill in theblack space associated with non-emissive portions of the display panel112, and thus reduce or eliminate the screen-door effect that wouldotherwise be visible to the eye 118. In other embodiments, the secondimage at time t₁ has different visual content than the first image attime t₀. In such embodiments, the eye 118 perceives the two images asoverlapping in a single super-resolution image with visual content ofthe second image filling in the black space associated with non-emissiveportions of the display panel 112. This reduces or eliminates the user'sability to perceive these non-emissive portions of the display panel112, thereby creating a perception of a display having an effectiveresolution of approximately twice the actual resolution of the displaypanel 112.

It should be noted that although the implementation 200 of the near-eyedisplay system 100 in FIG. 2 depicts a beam steering assembly having asingle beam steering element 214 for lateral light displacement, asnoted above the beam steering assembly 120 may employ a stack ofmultiple beam steering elements (e.g., beam steering elements 124, 126of FIG. 1) of differing configurations so as to provide multipledifferent lateral displacements, and thus provide the option to shiftmultiple successive images in different directions. For example,assuming the stack uses beam steering elements having a replicationfactor of two (e.g., beam steering element 214 of FIG. 2 that passesincident light to two different locations as either laterally displacedor not laterally displaced based on two corresponding states of the beamsteering element 214, activated or deactivated), a stack of four beamsteering elements allows for the replication and steering of eachsub-pixel of the display panel to four different positions (i.e., threelaterally displaced positions plus one original sub-pixel position inwhich all four beam steering elements are deactivated so that lightpasses through without any lateral displacement).

It should further be noted that although the example of FIG. 2 isdescribed in the context of a beam steering element 214 having areplication factor of two (i.e., deactivated to pass through without anylateral displacement or activated to replicate a sub-pixel for shiftingto another position), other embodiments may employ beam steeringelements having multiple different states. For example, instead of usinga stack of four beam steering elements that each have a replicationfactor of two, a single beam steering element (not shown) having areplication factor of four may be controlled by beam steering controller132 of FIG. 1 to switch between four different states that allow for thereplication and steering of each sub-pixel of the display panel to fourdifferent positions (i.e., three laterally displaced positions plus oneoriginal sub-pixel position in which all four beam steering elements aredeactivated so that light passes through without any lateraldisplacement).

In some embodiments, an amount of screen door effect perception (i.e.,metric of screen door effect severity) is represented by the equation:MTF(u)*CSF(u) for all spatial frequencies u, where MTF represents aModulation Transfer Function specifying how different spatialfrequencies are handled by the optics of a system (e.g., the near-eyedisplay system 100) and CSF represents a Contrast Sensitivity Functionrepresenting the eye's ability to discern between luminances ofdifferent levels in a static image. The product of eye's contrastsensitivity (i.e., how sensitive the eye is to certain spatialfrequencies, which turns out to be very sensitive to screen doorfrequency) and the spatial frequency content of pattern produced withreplication provides a system transfer function in which the larger thetransfer function is (for that specific spatial frequency u), the morescreen door will be perceived. Accordingly, reduction of the systemtransfer function can be represented by an optimization metric asprovided by equation (1) below:

$\begin{matrix}{\min\limits_{d,\theta}\frac{\int_{u_{m\; i\; n}}^{u_{m\;{ax}}}{{{PTF}( {u,d,\theta} )}{{CSF}(u)}{du}}}{\int_{u_{m\; i\; n}}^{u_{{ma}\; x}}{{{PTF}( {u,0,0} )}{{CSF}(u)}{du}}}} & (1)\end{matrix}$where u represents spatial frequency, d represents possible lateraldisplacement between replication spots, and θ represents rotation ofreplication/beam steering elements. The product of the equation providesa metric of how much screen door effect is perceivable after stacking anumber N of beam steering elements. For example, based on equation (1)for a beam steering element (which can also be referred to as a“filter”) having a replication factor of two (such as described hereinwith respect to FIG. 2), one filter results in approximately 41%perceptibility of the screen door effect, two filters results inapproximately 14% perceptibility of the screen door effect, threefilters results in approximately 7.5% perceptibility of the screen dooreffect, and four filters results in approximately 3.1% perceptibility ofthe screen door effect. Accordingly, increasing the number of beamsteering elements in a stack for the beam steering assembly generallyreduces perceptibility of the screen door effect.

The beam steering assembly is implementable using any of a variety ofsuitable optical beam steering elements capable of sub-pixel-scalesteering (i.e., steer replicated sub-pixels between positions based onstates of the beam steering element). For example, FIG. 3 is a diagramillustrating a diffractive beam steering element in accordance with someembodiments. In the example of FIG. 3, a beam steering element 300(e.g., one of the beam steering elements 124, 126 of FIG. 1 or beamsteering element 214 of FIG. 2) is a stacked pair of gratings includinga first grating 302 and a second grating 304 that splits and diffractsincident light into several beams traveling in different directions.

In some embodiments, the relationship between grating spacing and theangles of the incident and diffracted beams of light for beam steeringelement 300 is represented by equations (2) and (3):

$\begin{matrix}{{\theta = {\sin^{- 1}\frac{n\;\lambda}{D}}},} & (2) \\{{t = \frac{d}{\tan\;\theta}},} & (3)\end{matrix}$

where θ represents the diffractive angle between beams of diffractedlight (i.e., angular deflection of the diffracted beam, n represents theorder number, λ represents the wavelength of incident light, Drepresents the period of the gratings, t represents the distance betweenthe gratings, and d represents the optical lateral displacement betweenthe replicated sub-pixels. As discussed in more detail relative to FIG.2, the lateral displacement distance d is less than a pixel to fill inthe non-emissive portions between sub-pixels.

As shown, the first grating 302 of beam steering element 300 diffractsan incident beam of light 306 (e.g., light from a sub-pixel of thedisplay panel) into the ±1 first orders. The second grating 304 of thegrating pair further diffracts the light beams of ±1 first orders intothe ±2 second orders and reverses the angular deflection of thediffracted beams such that light beams passing through the secondgrating 304 (and therefore leaving the beam steering element 300) has adirection matching the incidence angle of the incident beam of light 306from sub-pixels of the display panel. In this manner, the beam steeringelement 300 replicates the original incident beam of light 306 andlaterally displaces the replicated beams. Various amplitude or phasegratings may be utilized for diffracting the incident light beam andthen reversing the angular deflection without departing from the scopeof this disclosure. Further, the gratings may be designed for single ormultiple diffraction orders to reduce thickness of the beam steeringelement.

In some embodiments, the relative spot intensities (i.e. diffractionefficiency) of spots (e.g., replicated beams of light) replicated bybeam steering element 300 is represented by equation (4):sin c(n*w/D)²  (4)where n represents diffraction order number, w/D is the open fraction ofthe grating, and sin c(x)=sin(π*x)/(π*x). Accordingly, the intensity ofthe replicated spots may be adjusted based on the open fraction ofgratings in beam steering element 300.

In another embodiment, FIG. 4 is a diagram illustrating a refractivebeam steering element in accordance with some embodiments. In theexample of FIG. 4, a beam steering element 400 (e.g., one of the beamsteering elements 124, 126 of FIG. 1 or beam steering element 214 ofFIG. 2) is a stacked pair of prisms including a first prism 402 and asecond prism 404 that refracts incident light into several beamstraveling in different directions. As shown, the first prism 402angularly disperses an incident beam of white light 406 from the displaypanel 112 into three angularly-deviated rays. As the refractive index ofprisms varies with the wavelength (i.e., color) of light, rays ofdifferent colors will be refracted differently and leave the first prism402, thereby separating the incident beam of white light 406 into red,green, and blue rays. The red ray R has a longer wavelength than thegreen ray G and the blue ray B, and therefore leaves the first prism 402with less angular deviation relative to the incident beam of white light406 than the other rays. Similarly, the green ray G has a longerwavelength than the blue ray B, and therefore leaves the first prism 402with less angular deviation relative to the incident beam of white light406 than the blue ray B.

As shown, the second prism 404 receives the three angularly-deviatedrays from the first prism 402 and reverses the angular deviations suchthat the rays leaving the second prism 404 (and therefore leaving thebeam steering element 400) have red, green, and blue colored raysdisplaced laterally while having a direction matching the incidenceangle of the incident beam of white light 406. In this manner, the beamsteering element 400 spreads out or changes the location of pixels at asub-pixel scale.

FIG. 5 a diagram illustrating another refractive beam steering elementin accordance with some embodiments. In the example of FIG. 5, a beamsteering element 500 (e.g., one of the beam steering elements 124, 126of FIG. 1 or beam steering element 214 of FIG. 2) includes a liquidcrystal cell 502 having liquid crystal molecules 504 oriented such as toform a birefringent material having a refractive index that depends onthe polarization and propagation direction of light. As shown, theliquid crystal molecules 504 are oriented to have their symmetry axes at45 degrees relative to the substrate plane. Accordingly, due to thedouble refraction phenomenon whereby a ray of incident light is splitbased on polarization into two rays taking slightly different paths, anincident beam of unpolarized light 506 is split into two rays 508, 510and steered to one of two deflection angles, depending on polarizationstate.

For the incident beam of unpolarized light 506, a first ray 508 having afirst polarization state (e.g., light whose polarization isperpendicular to the optic axis of the liquid crystal cell 502, referredto as “ordinary axis oriented”) passes through the liquid crystal cell502 without deflection. The second ray 510 having a second polarizationstate (e.g., light whose polarization is in the direction of the opticaxis of the liquid crystal cell 502, referred to as “extraordinary axisoriented”) is deflected and is passed with a lateral displacement d.

In some embodiments, the beam steering element 500 includes liquidcrystal molecules 504 that are oriented as illustrated in FIG. 5 andpolymerized such that the liquid crystal molecules 504 are linked to bestatic in that configuration, thereby forming a beam replicationassembly. In other embodiments, the beam steering element 500 furtherincludes a polarization switch (not shown) stacked on top of thepolymerized liquid crystal cell that switches polarization between twovalues so that the liquid crystal molecules 504 only received polarizedlight (rather than the beam of unpolarized light 506 illustrated in FIG.5). Accordingly, depending on the polarization of incident light, theincoming polarized light is either passed through or deviated (ratherthan passing both rays 508, 510 as illustrated in FIG. 5).

It should be noted that while embodiments implementing various beamsteering elements (such as the beam steering elements of FIG. 3-5) aredescribed herein for illustrative purposes, other suitable beam steeringelements capable of lateral (i.e., not angular) sub-pixel shifts may beimplemented in place of the beam steering elements described hereinunless otherwise noted.

FIG. 6 illustrates an example method 600 of operation of the near-eyedisplay system 100 for display of super-resolution imagery in accordancewith various embodiments. As described above relative to FIGS. 1-2, thenear-eye display system 100 takes advantage of the visual persistenceeffect to provide a time-multiplex display of shifted imagery so thateither a series of images is perceived by the user as either a singlesuper-resolution image or a native-resolution image with effectivelylarger pixels that conceal the non-emissive portions of the displaypanel 112. The method 600 illustrates one iteration of the process forrendering and displaying an image for one of the left-eye display 104 orright-eye display 106, and thus the illustrated process is repeatedlyperformed in parallel for each of the displays 104, 106 to generate anddisplay a different stream or sequence of frames for each eye atdifferent points in time, and thus provide a 3D, autostereoscopic VR orAR experience to the user.

The method 600 initiates at block 602 with determining a display imageto be generated and displayed at the display panel 112. In someembodiments, the rendering component 134 identifies the image content tobe displayed to the corresponding eye of the user as a frame. In atleast one embodiment, the rendering component 134 receives pose datafrom various pose-related sensors, such as a gyroscope, accelerometer,magnetometer, Global Positioning System (GPS) sensor, and the like todetermines a current pose of the apparatus 108 (e.g., HMD) used to mountthe displays 104, 106 near the user's eyes. From this pose data, the CPU136, executing the rendering program 144, can determine a correspondingcurrent viewpoint of the subject scene or object, and from thisviewpoint and graphical and spatial descriptions of the scene or objectprovided as rendering information 146, determine the imagery to berendered.

At block 604, the rendering program 144 manipulates the CPU 136 tosample the source image and generate a first array of pixelsrepresenting imagery to be rendered (e.g., as determined in block 602).The generated first array of pixels is subsequently transmitted to thedisplay panel 112 to be displayed.

At block 606, the beam steering controller 132 configures the beamsteering assembly 120 to be in a first configuration state while thedisplay controller 130 controls the display panel 112 facing the beamsteering assembly 120 to display the first array of pixels generated inblock 604. In some embodiments, such as described above relative to timeto in FIG. 2, the first configuration state of the beam steeringassembly is a deactivated state in which the optical beam steeringelement 214 allows the first array of pixels to be passed without anylateral displacements. In other embodiments, the first configurationstate of the beam steering assembly laterally displaces the first arrayof pixels such that they are not laterally aligned with the originaloptical path between the display panel 112 and the beam steeringassembly 120. Accordingly, the beam steering assembly, while in thefirst configuration state, imparts a first lateral displacement to thefirst array of pixels.

As explained above, for various beam steering devices, the switchingbetween configuration states for the beam steering assembly typicallyincludes activating or deactivating a particular combination of stagesof the stack of beam steering elements comprising the beam steeringassembly, such that the array of pixels leaving the beam steeringassembly is laterally shifted based on the configuration state. Notethat the process of block 606 may be performed concurrently with thecorresponding image generation at block 604.

At block 608, the rendering program 144 manipulates the CPU 136 tosample the source image and generate a second array of pixelsrepresenting imagery to be rendered (e.g., as determined in block 602).The generated second array of pixels is subsequently transmitted to thedisplay panel 112 to be displayed.

At block 610, the beam steering controller 132 configures the beamsteering assembly 120 to be in a second configuration state while thedisplay controller 130 controls the display panel 112 facing the beamsteering assembly 120 to display the second array of pixels generated inblock 608. In some embodiments, such as described above relative to timet₁ in FIG. 2, the second configuration state of the beam steeringassembly is an activated state in which the optical beam steeringelement 214 laterally displaces the second array of pixels such thatthey are not laterally aligned with first array of pixels.

As explained above, for various beam steering devices, the switchingbetween configuration states for the beam steering assembly typicallyincludes activating or deactivating a particular combination of stagesof the stack of beam steering elements comprising the beam steeringassembly, such that the array of pixels leaving the beam steeringassembly is laterally shifted based on the configuration state. Notethat the process of block 608 may be performed concurrently with thecorresponding image generation at block 610.

At block 612, the display controller 130 instructs the display panel todisplay the first and second array of pixels (e.g., as generated fromblocks 604-610) within a visual perception interval so that the firstand second first and second array of pixels are perceived by a user tobe a single image with an effective resolution that is higher than anative resolution of the display panel 112, thereby presenting asuper-resolution image.

It should be noted that although the method 600 of FIG. 6 is describedin the context of only combining two arrays of pixels that are laterallyshifted to each other to generate a super-resolution image, thoseskilled in the art will recognize that the number and rate of iterationsof the processes of blocks 604-610 may be varied increase the number oflaterally shifted images to be displayed by display panel 112 during thevisual persistence interval of the human eye. For example, assuming thebeam steering assembly 120 includes a stack of multiple different beamsteering elements (e.g., beam steering elements 124, 126 of FIG. 1) withdifferent configuration states, the processes of blocks 604-608 arerepeated for each of the different configuration states so that multiplearrays of pixels that are laterally shifted relative to each other maybe generated and displayed so as to be perceived as a singlesuper-resolution image by the user. Alternatively, rather thanresampling the source image between each lateral displacement of pixels,the same array of pixels can be shifted across the various configurationstates and displayed so as to be perceived as a singlestandard-resolution image with reduced screen-door effect by the user.

As demonstrated above, the various optical beam steering assembliesdescribed may be advantageously used to leverage the visual persistenceeffect of the human visual system to provide dynamicallytime-multiplexed, spatially shifted images that are perceived by a useras super-resolution images or native-resolution images with reducedperception of non-emissive portions of the display. Additionally, inother embodiments, the optical beam steering assemblies described may beused to passively replicate (i.e., without sending control voltages andchanging states of the beam steering assemblies) and spatially shiftincident light beams coming from the display panel to providenative-resolution images with reduced perception of non-emissiveportions of the display.

It will be appreciated that other embodiments provide for passivesuper-resolution without any time-multiplexing of images. FIG. 7 is adiagram illustrating a method of generating passive super-resolutionimages in accordance with some embodiments. As shown, a first image 702includes a plurality of pixels (with only four pixels 704, 706, 708, 710shown for ease of illustration). A second image 712 provides the samecontent data (e.g., pixels 704, 706, 708, 710) as the first image 702,but is laterally shifted in position relative to the first image 702.

For example, in some embodiments, the first image 702 and the secondimage 712 are generated by presenting unpolarized light from a displayscreen to the beam steering element 500 of FIG. 5. For the incidentunpolarized light, a first set of light rays having a first polarizationstate (e.g., light whose polarization is perpendicular to the optic axisof the beam steering element 500) passes through without deflection,thereby providing the first image 702. Additionally, for the sameincident unpolarized light, a second set of light rays having a secondpolarization state (e.g., light whose polarization is in the directionof the optic axis of the beam steering element 500) is deflected andpassed through with a lateral displacement d of a sub-pixel distance. Inthis example, the lateral displacement d is half a pixel in the x-axisdirection and half a pixel in the y-axis direction, thereby diagonallyshifting each of the pixels by half a pixel for the second image 712.

The first image 702 is overlaid with one or more sub-pixel shiftedcopies of itself (e.g., the second image 712) to generate a summed image714 which is perceivable as having improved resolution relative to thatof the first image 702 and the second image 712. It will be appreciatedthat depending on the overlap, certain sub-pixel portions of the summedimage 714 gets contributions from the same pixel value. For example, thesub-pixel portion 716 provides image data that is provided only by thevalue of pixel 704. Other sub-pixel portions of the summed image 714gets contributions from multiple different pixel values. For example,the sub-pixel portion 716 provides image data that is provided by boththe values of pixel 704 and pixel 706. In this manner, the effectiveresolution of the perceived image (i.e., summed image 714) is increasedwithout requiring time-multiplexing of images or coordinating therendering of images with varying the states of beam steering elements.

In some embodiments, certain aspects of the techniques described abovemay implemented by one or more processors of a processing systemexecuting software. The software comprises one or more sets ofexecutable instructions stored or otherwise tangibly embodied on anon-transitory computer readable storage medium. The software caninclude the instructions and certain data that, when executed by the oneor more processors, manipulate the one or more processors to perform oneor more aspects of the techniques described above. The non-transitorycomputer readable storage medium can include, for example, a magnetic oroptical disk storage device, solid state storage devices such as Flashmemory, a cache, random access memory (RAM) or other non-volatile memorydevice or devices, and the like. The executable instructions stored onthe non-transitory computer readable storage medium may be in sourcecode, assembly language code, object code, or other instruction formatthat is interpreted or otherwise executable by one or more processors.

A computer readable storage medium may include any storage medium, orcombination of storage media, accessible by a computer system during useto provide instructions and/or data to the computer system. Such storagemedia can include, but is not limited to, optical media (e.g., compactdisc (CD), digital versatile disc (DVD), Blu-Ray disc), magnetic media(e.g., floppy disc, magnetic tape, or magnetic hard drive), volatilememory (e.g., random access memory (RAM) or cache), non-volatile memory(e.g., read-only memory (ROM) or Flash memory), ormicroelectromechanical systems (MEMS)-based storage media. The computerreadable storage medium may be embedded in the computing system (e.g.,system RAM or ROM), fixedly attached to the computing system (e.g., amagnetic hard drive), removably attached to the computing system (e.g.,an optical disc or Universal Serial Bus (USB)-based Flash memory), orcoupled to the computer system via a wired or wireless network (e.g.,network accessible storage (NAS)).

Note that not all of the activities or elements described above in thegeneral description are required, that a portion of a specific activityor device may not be required, and that one or more further activitiesmay be performed, or elements included, in addition to those described.Still further, the order in which activities are listed are notnecessarily the order in which they are performed. Also, the conceptshave been described with reference to specific embodiments. However, oneof ordinary skill in the art appreciates that various modifications andchanges can be made without departing from the scope of the presentdisclosure as set forth in the claims below. Accordingly, thespecification and figures are to be regarded in an illustrative ratherthan a restrictive sense, and all such modifications are intended to beincluded within the scope of the present disclosure.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims. Moreover, the particular embodimentsdisclosed above are illustrative only, as the disclosed subject mattermay be modified and practiced in different but equivalent mannersapparent to those skilled in the art having the benefit of the teachingsherein. No limitations are intended to the details of construction ordesign herein shown, other than as described in the claims below. It istherefore evident that the particular embodiments disclosed above may bealtered or modified and all such variations are considered within thescope of the disclosed subject matter. Accordingly, the protectionsought herein is as set forth in the claims below.

What is claimed is:
 1. A near-eye display system, comprising: a displaypanel; and a beam steering assembly facing the display panel, the beamsteering assembly configurable in a plurality of configuration states todisplace a light beam incident on the beam steering assembly, wherein atleast one configuration state of the plurality of configuration statesreplicates the light beam into a plurality of laterally shifted beamsrelative to an optical path of the light beam, and wherein each of theplurality of laterally shifted beams includes a different lateral shift.2. The near-eye display system of claim 1, wherein: the beam steeringassembly comprises a stacked grating pair configured to diffract thelight beam, wherein a first grating of the stacked grating pair facingthe display panel splits the light beam incident on the beam steeringassembly into two or more angularly deflected light beams, and furtherwherein a second grating of the stacked grating pair angularly deflectseach of the two or more angularly deflected light beams to be parallelto the optical path of the light beam incident on the beam steeringassembly.
 3. The near-eye display system of claim 1, wherein: the beamsteering assembly comprises a stacked prism pair configured to refractthe light beam, wherein a first prism of the stacked prism pair receivesthe light beam from the display panel and angularly disperses the lightbeam into a plurality of color separated rays, and further wherein asecond prism of the stacked prism pair angularly deflects each of theplurality of color separated rays to be parallel to the optical path ofthe light beam incident on the beam steering assembly.
 4. The near-eyedisplay system of claim 1, wherein: the beam steering assembly comprisesa liquid crystal cell configured to laterally shift the light beamincident on the beam steering assembly based on a polarization state ofthe light beam.
 5. The near-eye display system of claim 1, furthercomprising: a display controller coupled to the display panel, thedisplay controller to drive the display panel to display a sequence ofimages; and a beam steering controller coupled to the beam steeringassembly, the beam steering controller to control the beam steeringassembly to impart a different lateral shift for each displayed image ofthe sequence of images.
 6. The near-eye display system of claim 5,wherein: the sequence of images is displayed in a period of time lessthan a visual persistence interval so that the sequence of images isperceived by a user as a single image having an effective resolutionhigher than a native resolution of the display panel.
 7. The near-eyedisplay system of claim 5, wherein: the sequence of images includes twoor more images having the same visual content and which are displayed ina period of time less than a visual persistence interval so that thesequence of images is perceived by a user as a single image having aresolution of the display panel and having pixels with an apparent sizethat is larger than an actual size of the pixels of the display panel.8. The near-eye display system of claim 5, wherein: the beam steeringassembly comprises a stack of beam steering elements, each beam steeringelements configurable to impart a corresponding lateral shift to a pixelgrid for each image of the sequence of images so that each image of thesequence of images is perceptible as a single image comprising aplurality of shifted pixel grids and having pixels with an apparent sizethat is larger than an actual size of the pixels of the display panel.9. The near-eye display system of claim 1, wherein: the beam steeringassembly comprises a stack of beam steering elements, each beam steeringelements configurable to impart a corresponding lateral shift to thelight beam incident on the beam steering assembly when each beamsteering element is activated.
 10. The near-eye display system of claim1, wherein the beam steering assembly comprises a beam steering elementconfigurable in multiple configuration states of the plurality ofconfiguration states, wherein each of the multiple configuration statesincludes a different lateral shift of the light beam relative to theoptical path of the light beam.
 11. In a near-eye display system, amethod comprising: configuring a beam steering assembly in at least oneof a plurality of configuration states so that the beam steeringassembly displaces a light beam incident on the beam steering assemblyby laterally shifting the light beam relative to an optical path of thelight beam, wherein a first configuration state of the plurality ofconfiguration states replicates the light beam into a plurality oflaterally shifted beams, and wherein each of the plurality of laterallyshifted beams includes a different lateral shift.
 12. The method ofclaim 11, further comprising: controlling a display panel facing thebeam steering assembly to display a first image while the beam steeringassembly is in the first configuration state; and controlling the beamsteering assembly to impart a first lateral shift for the first image.13. The method of claim 12, further comprising: controlling the displaypanel facing the beam steering assembly to display a second image; andsignaling the beam steering assembly to enter a second configurationstate of the plurality of configuration states to impart a secondlateral shift for the second image.
 14. The method of claim 13, furthercomprising: controlling the display panel to display the first andsecond images within a visual perception interval so that the first andsecond images are perceptible a single image with an effectiveresolution that is higher than a native resolution of the display panel.15. The method of claim 13, wherein: the first and second images containthe same visual content and which are displayed in a period of time lessthan a visual persistence interval so that the first and second imagesare perceptible as a single image having a resolution of the displaypanel and having pixels with an apparent size that is larger than anactual size of the pixels of the display panel.
 16. The method of claim11, further comprising: passing the plurality of laterally shifted beamsfor display so that the plurality of laterally shifted beams areperceptible as a single image having a resolution of a display panelfacing the beam steering assembly and having pixels with an apparentsize that is larger than an actual size of the pixels of the displaypanel.
 17. A rendering system, comprising: at least one processor; abeam steering assembly facing a display panel; and a storage componentto store a set of executable instructions, the set of executableinstructions configured to manipulate the at least one processor tosample a source image to render a first image comprising a first arrayof pixels, the set of executable instructions further to configure thebeam steering assembly in at least one of a plurality of configurationstates so that the first array of pixels are laterally shifted relativeto an optical path between the display panel and the beam steeringassembly prior to presentation to a user, wherein at least oneconfiguration state of the plurality of configuration states replicatesthe first array of pixels into a plurality of laterally array of pixels.18. The rendering system of claim 17, wherein the set of executableinstructions are further configured to manipulate the at least oneprocessor to: resample the source image to render a second imagecomprising a second array of pixels; and signal a display controllercoupled to the display panel to present both the first image and thesecond image in a period of time less than a visual persistence intervalso that the first and second array of pixels are perceptible as a singleimage.
 19. The rendering system of claim 18, wherein the set ofexecutable instructions are further configured to manipulate the atleast one processor to: render the first image and the second image tocontain different visual content so that the single image is perceptibleas having an effective resolution higher than a native resolution of thedisplay panel.
 20. The rendering system of claim 18, wherein the set ofexecutable instructions are further configured to manipulate the atleast one processor to: render the first image and the second image tocontain the same visual content so that the single image is perceptibleas having a resolution of the display panel and having pixels with anapparent size that is larger than an actual size of the pixels of thedisplay panel.